CIS 
Properties of the Cissoid .-~~ It follows from 
ie genesis, that drawing the right lines P M, 
i L, perpendicular to A B, the lines A K, P N, 
P, PM, as also AP, P N, A K, KL, are 
rmtinual proportionals, and therefore that 
L Iv = P B, and P N = 1 K. If the diameter 
LB — a, the absciss AP = .r, and the ordi- 
nate PM = ?/, then is x: a— x \:y 2 : .i* or j: 3 = 
j _ , X f, which is the equation of the curve. 
After the same manner it appears that the 
fcissoid A M O, bisects tiie semicircle AOB. 
Bir Isaac Newton, in his last letter to Mr. 
Leibnitz, has shewn how to find a right line 
equal to one of the legs of this curve, by 
Leans of the hyperbola, hut suppressed the 
investigation, which however may be seen 
in his fluxions. The cissoidal space con- 
tained under the diameter A B, the asymptote 
BC, and the curve AO Z of the cissoid, is 
triple that of the generating circle AOB. 
See Dr. Wallis’s mathematical works, A ol. I. 
p. 545, et seq. 
! CISSUS, the wild grape, a genus of the 
monogynia order, in the tetrandria class of 
Wants, and in the natural method ranking 
under the 46th. order, hederacew. The 
berry is monospermous, surrounded by the 
'icalvx, and a quadripartite corolla. There 
are 15 species, natives of Jamaica, and some 
of the other islands in the warmest parts of 
America and the East Indies. They send 
out slender branches, having tendrils at their 
joints; by which they fasten to the neighbour- 
ing trees, bushes, and any other support, 
mounting to a considerable height. 1 Ire 
fruit of some of the species is eaten by the 
negroes. 
: CISTERCIANS, in church-history, a re- 
ligious order founded in the eleventh cen- 
tury by St. Robert, a benedictine. They 
became so powerful, that they governed al- 
most all Europe, both in spirituals and tem- 
porals. Cardinal de Vitri describing their 
observances says, they neither wore skins 
nor shirts, nor ever ate flesh except in sick- 
ness; and abstained from fish, eggs, milk, 
and cheese. They lay upon straw beds, in 
their tunics and cowls: They rose at midnight 
to prayers; they spent the day in labour, 
reading, and prayer; and in all their exercises 
observed a continual silence. The habit of 
the Cistercian monks is a white robe, in the 
nature of a cassock, with a black scapulary 
land hood, and is girt with a woollen girdle. 
The nuns wear a white tunic, and a black 
scapulary and girdle. 
CISTUS, rockrose, a genus of the mono- 
gvnia order, in the polyandria class of plants, 
and in the natural method ranking under the 
1 20th order, rotacete. The corolla is penta- 
J petalous ; the calyx pentaphyllous, with two 
; of its leaves smaller than the rest. The seeds 
ij are contained in a capsule. I here are 66 
[ species, most of them natives of the southern 
parts of Europe, but many of thorn hardy 
| enough to bear the open air in this country. 
I They are beautiful evergreen shrubs, gene- 
I rally very branchy quite from the bottom, 
. and forming diffused heads. They are very 
ornamental in gardens : not only as ever- 
greens, making a fine variety at all seasons 
with the Naves of different figures, sizes, and 
shades of green and white ; but also as first- 
rate flowering shrubs, being very profuse in 
most elegant flowers of white, purple, and 
yellow colours. These flowers last only for 
ene day; biff there is a continual succession 
C 1 T 
of new ones for a month or six weeks on the 
same plant; and when there are different 
species, they exhibit a constant bloom for 
near three months. They are propagated 
either by seeds or cuttings, and thrive best 
in a dry soil. Their proper situation in shrub- 
bery works should be towards the front ol 
the clumps and other compartments, in as- 
semblage with the choicest shrubs of similar 
growth, disposing them so as to make a va- 
riety, and to have shelter from the other 
plants, but they ought by no means to be 
crowded. Gum labdanum is found upon a 
species of cistus which grows naturally in the 
Levant, and is therefore called labdaniferus. 
Cl l 'A DEL, a place fortified with four, 
five, or six bastions, built on a convenient 
ground near a city, that it may command it 
in case of a rebellion. The. city therefore is 
not fortified on the part opposite to the ci- 
tadel, though the citadel is against the city. 
The best form for a citadel is a pentagon, a 
square being too weak, and a hexagon too 
large. 
CITATION, in ecclesiastical courts, is 
the same with summons in civil courts. A 
person is not to be cited out of the diocese 
where lie lives, unless it be by the arch- 
bishop in default of the ordinary, or where 
the ordinary is party to the suit, and in cases 
of appeal, 
C1THAREXYLUM, fiddle-wood, a ge- 
nus of the angiospennia order, in the didy- 
namia class of plants, and in the natural me- 
thod ranking under the 40th order, perso- 
nate. The calyx is quinquedentated, cam- 
panulated, wheel-shaped, with its segments 
villous, on the upper side equal. The fruit 
is a dispermous berry; the seeds bilocular. 
There are five species, natives of the warmer 
parts of America, where they grow to be 
large trees, and are adorned with white 
flowers growing in spikes. In Britain they 
appear only as shrubs, and must be con- 
stantly retained in the stove, where they 
make a fine appearance, being beautiful ever- 
greens. They may be propagated either by 
seeds or cuttings. 
CITRINES, in natural history, a peculiar 
species of sprig crystal, which is of a 
beautiful yellow. Many of the common 
crystals, when in the neighbourhood, of lead 
mines, are liable to be accidentally tinged 
yellow, by an admixture of the particles of 
that metal; and all these, whether finer or 
coarser, have been too frequently confounded 
together under the name citrine; but Dr. 
Hill has ascertained this to be a peculiar 
species of crystal different from all the 
others in form as well as in colour; and distin- 
guished by the name of ellipomacrostylum 
lucidum flavescens, pyramido brevi. It is 
never found colourless like the other crys- 
tals, but has great variety of tinges, from that 
of the deeper ochres to a pale lemon-colour. 
It is sometimes found in Bohemia. The py- 
ramid of this crystal is always finer than the 
column. 
CITRUS, the citron, orange, and lemon 
tree, a genus of the polyadelphia class and the 
icosandria order of plants. The calyx is quin- 
quefid ; the petals oblong, and five in num- 
ber; the anthers are 20, filaments united 
into various bodies ; fruit nine-celled. There 
are five species, with many varieties, viz. 
1 . Citrus aurantium, the orange : of which 
the varieties are, 1. Seville orange. This is 
C I T 307 
a very handsome tree, and the hardiest of 
any ; " as in this country it shoots freely, pro- 
duces large and beautiful leaves, flowers 
stronger, &c. 1 he fruit is large, rough-rind- 
ed, and sour, of excellent quality for econo- 
mical uses. 2. The China orange. Ibis 
tree has moderately-sized leaves, and a 
smooth, thin-rinded, sweet fruit, of which 
there are several varieties in warm countries, 
whey they grow in the open ground. 3. '1 be 
forbidden-fruit tree, in trunk, leaves, and 
flowers, very much resembles the common 
orange-tree; but the fruit when ripe is larger 
and longer than the biggest orange, bee 
Plate. It lias somewhat the taste of shad- 
dock, but far exceeds that, as well as the. 
best orange, in its delicious taste and flavour. 
4. r ] he horned orange is a tree ol moderate 
size, producing fruit which divide, and the 
rind runs out into divisions like horns. 5X1 he 
hermaphrodite orange is a common sized 
tree, producing fruit shaped partly like an 
orange and partly like a citron. 6. I he 
dwarf orange tree, or nutmeg orange, has a 
long stem and small bushy head, growing 
two or three feet high ; small oval leaves in 
clusters; and numerous flowers in clusters, 
covering the branches, succeeded by very 
small fruit. 
2. Citrus medica, the citron-tree. The 
varieties are, 1. citron-tree with sour fruit; 
2. with sweetish fruit; 3. with long fruit; 
4. with warted fruit; 5. with recurved fruit ; 
and 6. with blotched leaves. 
The lemon-tree is accounted a variety of 
the citron. The varieties of lemon are,. 1. the 
lemon-tree with sour fruit; 2. with sweetish 
fruit; 3. with very large fruit, called imperial 
lemon; 4. with pear-shaped fruit; 5. with fur- 
rowed fruit; 6. with clustered fruit; 7. with 
childing fruit; 8. with whitish fruit; 9. with 
tricolar striped fruit; 10. with silver-striped 
leaves ; and 11. with double flowers. 
These are the most remarkable varieties 
of file species of citrus; but besides these 
there are a great number of others ; and in- 
deed in those countries where they grow na- 
turally, the varieties may be multiplied with- 
out end, like those of our apples and pears. 
The flowers of all the species and varieties are 
formed each of five spreading petals, appear- 
ing here principally in May and June, and 
the ’fruit continues setting in June and July,, 
and ripens the year following. 
3. Citrus trifoliata, is a thorny shrub grow- 
ing naturally in Japan, where it is likewise 
known by the names of gees, and karatals 
banna. The trunk acquires by age and cul- 
ture the thickness of a tree. The flowers,, 
which resemble those of the medlar, proceed 
singly from the arm-pits of the leaves, are 
white, possessed of no great degree of fra- 
grance, and consist of five petals. The fruit is 
equally beautiful with a middle-sized orange;, 
their internal structure is also pretty much 
the same; only the pulp is glutinous, of an 
unpleasant smell, and a harsh disagreeable 
taste. The seeds have the same taste with 
the pulp, and are shaped exactly like those 
of the orange. 
4. Citrus decumana, or shaddock, which 
derives its name from captain Shaddock* 
who brought it from the East to the West 
Indies. 
5. Citrus japonica, the fruit of which is; 
no larger than a cherry, but very sweet andi 
pleasant. 
